Final video is faster than what I see in the viewport
I would never trust playback in blender to be a representation of anything resembling real-time. It really depends on how powerful your computer is. For the most part, preview in the 3d viewport it is usually slower unless you are visualizing on a very simplified mode, like Bunding Box, maybe wireframe and with low settings on modifiers or anything that can help your computer cope with the demands of the scene. If the speed looks fast when you play using frame dropping i probably means that the animation might indeed need to be slowed down. When using Frame Dropping the computer is trying to target the desired frame rate by not generating all of the frames in the animation. To do tests renders use OpenGL rendering (as suggested by @moonboots) It will give you a better sense of what your animation looks like in real-time.

You can of course change the final output's speed by altering the Time-Remapping See: How can I modify the frame rate without changing the overall animation speed?